In recognizing Kenyan Geoffrey Mutai's mark of 2:03:02 at the 2011 Boston Marathon as (at the time) the fastest Marathon ever run, the IAAF has noted: Due to the elevation drop and point-to-point measurements of the Boston course, performances [on that course] are not eligible for World record consideration..
There are three types of embryonic cells; endoderm, mesoderm, and ectoderm. In the human body there are many different types of cells, more than two. They are grouped into tissue types. We have four different tissues; connective, nervous, muscular, and epithelial. The two major groups of cell types in the human body are somatic cells and gamete cells. There are three types of embryonic cells; endoderm, mesoderm, and ectoderm. In the human body there are many different types of cells, more than two. They are grouped into tissue types. We have four different tissues;  connective, nervous, muscular, and epithelial.
The nervous system is built from two broad categories of cells, neurones and glial cells. The glial cells outnumber the neurones and the two cell types occupy a comparable amount of space in nervous tissue.The main glial cell types are, in the central nervous system, astrocytes and oligodendrocytes and, in the peripheral nervous system, Schwann cells, enteric glial cells and satellite cells.lia also maintain appropriate concentrations of ions and neurotransmitters in the neuronal environment. Increasing body of evidence indicates that glial cells are essential regulators of the formation, maintenance and function of synapses, the key functional unit of the nervous system.